Content of ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS in our journal

Published in last 1 year |  In last 2 years |  In last 3 years |  All Please wait a minute... For selected: Download citations EndNote Ris BibTeX Toggle thumbnails Select On-chip ultrafast stackable dielectric laser positron accelerator Bin Sun(孙斌), Yangfan He(何阳帆), Chenhao Pan(潘晨浩), Sijie Fan(樊思劼), Du Wang(王度), Shaoyi Wang(王少义), and Zongqing Zhao(赵宗清) Chin. Phys. B, 2024, 33 (3): 034101.   DOI: 10.1088/1674-1056/ad188e Abstract （51）   HTML （0）    PDF （2095KB）（40）       Knowledge map    We present a first on-chip positron accelerator based on dielectric laser acceleration. This innovative approach significantly reduces the physical dimensions of the positron acceleration apparatus, enhancing its feasibility for diverse applications. By utilizing a stacked acceleration structure and far-infrared laser technology, we are able to achieve a seven-stage acceleration structure that surpasses the distance and energy gain of using the previous dielectric laser acceleration methods. Additionally, we are able to compress the positron beam to an ultrafast sub-femtosecond scale during the acceleration process, compared with the traditional methods, the positron beam is compressed to a greater extent. We also demonstrate the robustness of the stacked acceleration structure through the successful acceleration of the positron beam. Select Singular optical propagation properties of two types of one-dimensional anti-PT-symmetric periodic ring optical waveguide networks Yanglong Fan(樊阳龙), Xiangbo Yang(杨湘波), Huada Lian(练华达), Runkai Chen(陈润楷),Pengbo Zhu(朱蓬勃), Dongmei Deng(邓冬梅), Hongzhan Liu(刘宏展), and Zhongchao Wei(韦中超) Chin. Phys. B, 2024, 33 (3): 034201.   DOI: 10.1088/1674-1056/ad12ab Abstract （32）   HTML （0）    PDF （3199KB）（14）       Knowledge map    Two types of one-dimensional (1D) anti-PT-symmetric periodic ring optical waveguide networks, consisting of gain and loss materials, are constructed. The singular optical propagation properties of these networks are investigated. The results show that the system composed of gain materials exhibits characteristics of ultra-strong transmission and bidirectional reflection. Conversely, the system composed of loss materials demonstrates equal transmittance and reflectance at some frequencies. In both the systems, a new type of total reflection phenomenon is observed. When the imaginary part of the refractive indices of waveguide segments is smaller than 10-5, the system shows bidirectional transparency with the transmittance tending to be 1 and reflectivity to be smaller than 10-8 at some bands. When the refractive indices of the waveguide segments are real, the system will be bidirectional transparent at the full band. These findings may deepen the understanding of anti-PT-symmetric optical systems and optical waveguide networks, and possess potential applications in efficient optical energy storage, ultra-sensitive optical filters, ultra-sensitive all-optical switches, integrated optical chips, stealth physics, and so on. Select Simultaneous guidance of electromagnetic and elastic waves via glide symmetry phoxonic crystal waveguides Lin-Lin Lei(雷林霖), Ling-Juan He(何灵娟), Qing-Hua Liao(廖清华), Wen-Xing Liu(刘文兴), and Tian-Bao Yu(于天宝) Chin. Phys. B, 2024, 33 (3): 034202.   DOI: 10.1088/1674-1056/ad0ec7 Abstract （26）   HTML （0）    PDF （6721KB）（23）       Knowledge map    A phoxonic crystal waveguide with the glide symmetry is designed, in which both electromagnetic and elastic waves can propagate along the glide plane at the same time. Due to the glide symmetry, the bands of the phoxonic crystal super-cell degenerate in pairs at the boundary of the Brillouin zone. This is the so-called band-sticking effect and it causes the appearance of gapless guided-modes. By adjusting the magnitude of the glide dislocation the edge bandgaps, the bandgap of the guided-modes at the boundary of the Brillouin zone, can be further adjusted. The photonic and phononic guided-modes can then possess only one mode for a certain frequency with relatively low group velocities, achieving single-mode guided-bands with relatively flat dispersion relationship. In addition, there exists acousto-optic interaction in the cavity constructed by the glide plane. The proposed waveguide has potential applications in the design of novel optomechanical devices. Select A polarization sensitive interferometer: Delta interferometer Chao-Qi Wei(卫超奇), Jian-Bin Liu(刘建彬), Yi-Fei Dong(董翼飞), Yu-Nong Sun(孙雨农), Yu Zhou(周宇), Huai-Bin Zheng(郑淮斌), Yan-Yan Liu(刘严严), Xiu-Sheng Yan(闫秀生), Fu-Li Li(李福利), and Zhuo Xu(徐卓) Chin. Phys. B, 2024, 33 (3): 034203.   DOI: 10.1088/1674-1056/acf996 Abstract （45）   HTML （0）    PDF （966KB）（49）       Knowledge map    A new type of polarization sensitive interferometer is proposed, named the Delta interferometer, inspired by its geometry resembling the Greek letter Delta. The main difference between the Delta interferometer and other existing interferometers, such as Michelson, Mach-Zehnder and Young's double-slit interferometers, is that the two interfering paths are asymmetrical in the Delta interferometer. The visibility of the first-order interference pattern observed in the Delta interferometer is dependent on the polarization of the incidental light. Optical coherence theory is employed to interpret this phenomenon and single-mode continuous-wave laser light is employed to verify the theoretical predictions. The theoretical and experimental results are consistent. The Delta interferometer is a perfect tool to study the reflection of electromagnetic fields in different polarizations and may find applications in polarization-sensitive scenarios. Select Efficient single-pixel imaging encrypted transmission based on 3D Arnold transformation Zhen-Yu Liang(梁振宇), Chao-Jin Wang(王朝瑾), Yang-Yang Wang(王阳阳), Hao-Qi Gao(高皓琪), Dong-Tao Zhu(朱东涛), Hao-Li Xu(许颢砾), and Xing Yang(杨星) Chin. Phys. B, 2024, 33 (3): 034204.   DOI: 10.1088/1674-1056/acf204 Abstract （45）   HTML （0）    PDF （2797KB）（35）       Knowledge map    Single-pixel imaging (SPI) can transform 2D or 3D image data into 1D light signals, which offers promising prospects for image compression and transmission. However, during data communication these light signals in public channels will easily draw the attention of eavesdroppers. Here, we introduce an efficient encryption method for SPI data transmission that uses the 3D Arnold transformation to directly disrupt 1D single-pixel light signals and utilizes the elliptic curve encryption algorithm for key transmission. This encryption scheme immediately employs Hadamard patterns to illuminate the scene and then utilizes the 3D Arnold transformation to permutate the 1D light signal of single-pixel detection. Then the transformation parameters serve as the secret key, while the security of key exchange is guaranteed by an elliptic curve-based key exchange mechanism. Compared with existing encryption schemes, both computer simulations and optical experiments have been conducted to demonstrate that the proposed technique not only enhances the security of encryption but also eliminates the need for complicated pattern scrambling rules. Additionally, this approach solves the problem of secure key transmission, thus ensuring the security of information and the quality of the decrypted images. Select Diffraction deep neural network-based classification for vector vortex beams Yixiang Peng(彭怡翔), Bing Chen(陈兵), Le Wang(王乐), and Shengmei Zhao(赵生妹) Chin. Phys. B, 2024, 33 (3): 034205.   DOI: 10.1088/1674-1056/ad0142 Abstract （39）   HTML （0）    PDF （1189KB）（26）       Knowledge map    The vector vortex beam (VVB) has attracted significant attention due to its intrinsic diversity of information and has found great applications in both classical and quantum communications. However, a VVB is unavoidably affected by atmospheric turbulence (AT) when it propagates through the free-space optical communication environment, which results in detection errors at the receiver. In this paper, we propose a VVB classification scheme to detect VVBs with continuously changing polarization states under AT, where a diffractive deep neural network (DDNN) is designed and trained to classify the intensity distribution of the input distorted VVBs, and the horizontal direction of polarization of the input distorted beam is adopted as the feature for the classification through the DDNN. The numerical simulations and experimental results demonstrate that the proposed scheme has high accuracy in classification tasks. The energy distribution percentage remains above 95% from weak to medium AT, and the classification accuracy can remain above 95% for various strengths of turbulence. It has a faster convergence and better accuracy than that based on a convolutional neural network. Select Enhancing the Goos-Hänchen shift based on quasi-bound states in the continuum through material asymmetric dielectric compound gratings Xiaowei Jiang(江孝伟), Bin Fang(方彬), and Chunlian Zhan(占春连) Chin. Phys. B, 2024, 33 (3): 034206.   DOI: 10.1088/1674-1056/acf661 Abstract （37）   HTML （1）    PDF （3042KB）（8）       Knowledge map    Quasi-bound state in the continuum (QBIC) resonance is gradually attracting attention and being applied in Goos-Hänchen (GH) shift enhancement due to its high quality (Q) factor and superior optical confinement. Currently, symmetry-protected QBIC resonance is often achieved by breaking the geometric symmetry, but few cases are achieved by breaking the material symmetry. This paper proposes a dielectric compound grating to achieve a high Q factor and high-reflection symmetry-protectede QBIC resonance based on material asymmetry. Theoretical calculations show that the symmetry-protected QBIC resonance achieved by material asymmetry can significantly increase the GH shift up to -980 times the resonance wavelength, and the maximum GH shift is located at the reflection peak with unity reflectance. This paper provides a theoretical basis for designing and fabricating high-performance GH shift tunable metasurfaces/dielectric gratings in the future. Select Generation of orbital angular momentum hologram using a modified U-net Zhi-Gang Zheng(郑志刚), Fei-Fei Han(韩菲菲), Le Wang(王乐), and Sheng-Mei Zhao(赵生妹) Chin. Phys. B, 2024, 33 (3): 034207.   DOI: 10.1088/1674-1056/ad12aa Abstract （35）   HTML （0）    PDF （3925KB）（34）       Knowledge map    Orbital angular momentum (OAM) holography has become a promising technique in information encryption, data storage and opto-electronic computing, owing to the infinite topological charge of one single OAM mode and the orthogonality of different OAM modes. In this paper, we propose a novel OAM hologram generation method based on a densely connected U-net (DCU), where the densely connected convolution blocks (DCB) replace the convolution blocks of the U-net. Importantly, the reconstruction process of the OAM hologram is integrated into DCU as its output layer, so as to eliminate the requirement to prepare training data for the OAM hologram, which is required by conventional neural networks through an iterative algorithm. The experimental and simulation results show that the OAM hologram can rapidly be generated with the well-trained DCU, and the reconstructed image's quality from the generated OAM hologram is significantly improved in comparison with those from the Gerchberg-Saxton generation method, the Gerchberg-Saxton based generation method and the U-net method. In addition, a 10-bit OAM multiplexing hologram scheme is numerically demonstrated to have a high capacity with OAM hologram. Select Engineering the spectra of photon triplets generated from micro/nanofiber Chuan Qu(瞿川), Dongqin Guo(郭东琴), Xiaoxiao Li(李笑笑), Zhenqi Liu(刘振旗), Yi Zhao(赵义), Shenghai Zhang(张胜海), and Zhengtong Wei(卫正统) Chin. Phys. B, 2024, 33 (3): 034208.   DOI: 10.1088/1674-1056/ad1c5d Abstract （46）   HTML （0）    PDF （1375KB）（27）       Knowledge map    Quantum light sources are the core resources for photonics-based quantum information processing. We investigate the spectral engineering of photon triplets generated by third-order spontaneous parametric down-conversion in micro/nanofiber. The phase mismatching at one-third pump frequency gives rise to non-degenerate photon triplets, the joint spectral intensity of which has an elliptical locus with a fixed eccentricity of √6/3. Therefore, we propose a frequency-division scheme to separate non-degenerate photon triplets into three channels with high heralding efficiency for the first time. Choosing an appropriate pump wavelength can compensate for the fabrication errors of micro/nanofiber and also generate narrowband, non-degenerate photon triplet sources with a high signal-to-noise ratio. Furthermore, the long-period micro/nanofiber grating introduces a new controllable degree of freedom to tailor phase matching, resulting from the periodic oscillation of dispersion. In this scheme, the wavelength of photon triplets can be flexibly tuned using quasi-phase matching. We study the generation of photon triplets from this novel perspective of spectrum engineering, and we believe that this work will accelerate the practical implementation of photon triplets in quantum information processing. Select Versatile and controlled quantum teleportation network Yao-Yao Zhou(周瑶瑶), Peng-Xian Mei(梅鹏娴), Yan-Hong Liu(刘艳红), Liang Wu(吴量), Yan-Xiang Li(李雁翔), Zhi-Hui Yan(闫智辉), and Xiao-Jun Jia(贾晓军) Chin. Phys. B, 2024, 33 (3): 034209.   DOI: 10.1088/1674-1056/ad1981 Abstract （39）   HTML （0）    PDF （2460KB）（41）       Knowledge map    A quantum teleportation network involving multiple users is essential for future quantum internet. So far, controlled quantum teleportation has been demonstrated in a three-user network. However, versatile and controlled quantum teleportation network involving more users is in demand, which satisfies different combinations of users for practical requirements. Here we propose a highly versatile and controlled teleportation network that can switch among various combinations of different users. We use a single continuous-variable six-partite Greenberger-Horne-Zeilinger (GHZ) state to realize such a task by choosing the different measurement and feedback operations. The controlled teleportation network, which includes one sub-network, two sub-networks and three sub-networks, can be realized for different application of user combinations. Furthermore, the coherent feedback control (CFC) can manipulate and improve the teleportation performance. Our approach is flexible and scalable, and would provide a versatile platform for demonstrations of complex quantum communication and quantum computing protocols. Select On the generation of high-quality Nyquist pulses in mode-locked fiber lasers Yuxuan Ren(任俞宣), Jinman Ge(葛锦蔓), Xiaojun Li(李小军), Junsong Peng(彭俊松), and Heping Zeng(曾和平) Chin. Phys. B, 2024, 33 (3): 034210.   DOI: 10.1088/1674-1056/acfa87 Abstract （52）   HTML （0）    PDF （966KB）（33）       Knowledge map    Nyquist pulses have wide applications in many areas, from electronics to optics. Mode-locked lasers are ideal platforms to generate such pulses. However, how to generate high-quality Nyquist pulses in mode-locked lasers remains elusive. We address this problem by managing different physical effects in mode-locked fiber lasers through extensive numerical simulations. We find that net dispersion, linear loss, gain and filter shaping can affect the quality of Nyquist pulses significantly. We also demonstrate that Nyquist pulses experience similariton shaping due to the nonlinear attractor effect in the gain medium. Our work may contribute to the design of Nyquist pulse sources and enrich the understanding of pulse shaping dynamics in mode-locked lasers. Select Estimating the yield stress of soft materials via laser-induced breakdown spectroscopy Shuhang Gong(龚书航), Yaju Li(李亚举), Dongbin Qian(钱东斌), Jinrui Ye(叶晋瑞), Kou Zhao(赵扣), Qiang Zeng(曾强), Liangwen Chen(陈良文), Shaofeng Zhang(张少锋), Lei Yang(杨磊), and Xinwen Ma(马新文) Chin. Phys. B, 2024, 33 (3): 034211.   DOI: 10.1088/1674-1056/ad12a9 Abstract （22）   HTML （0）    PDF （1284KB）（5）       Knowledge map    Taking three typical soft samples prepared respectively by loose packings of 77-, 95-, and 109-μm copper grains as examples, we perform an experiment to investigate the energy-dependent laser-induced breakdown spectroscopy (LIBS) of soft materials. We discovered a reversal phenomenon in the trend of energy dependence of plasma emission intensity: increasing initially and then decreasing separated by a well-defined critical energy. The trend reversal is attributed to the laser-induced recoil pressure at the critical energy just matching the sample's yield strength. As a result, a one-to-one correspondence can be well established between the samples' yield stress and the critical energy that is easily obtainable from LIBS measurements. This allows us to propose an innovative method for estimating the yield stress of soft materials via LIBS with attractive advantages including in-situ remote detection, real-time data collection, and minimal destructive to sample. Select Tunable spectral continuous shift of high-order harmonic generation in atoms by a plasmon-assisted shaping pulse Yuan Wang(王源), Yulong Li(李玉龙), Yue Qiao(乔月), Na Gao(高娜),Fu-Ming Guo(郭福明), Zhou Chen(陈洲), Lan-Hai He(赫兰海),Yu-Jun Yang(杨玉军), Xi Zhao(赵曦), and Jun Wang(王俊) Chin. Phys. B, 2024, 33 (3): 034212.   DOI: 10.1088/1674-1056/ad10fb Abstract （43）   HTML （0）    PDF （5966KB）（28）       Knowledge map    We delve into the phenomenon of high-order harmonic generation within a helium atom under the influence of a plasmon-assisted shaping pulse. Our findings reveal an intriguing manipulation of the frequency peak position in the harmonic emission by adjusting the absolute phase parameter within the frequency domain of the shaping pulse. This phenomenon holds potential significance for experimental setups necessitating precisely tuned single harmonics. Notably, we observe a modulated shift in the created harmonic photon energy, spanning an impressive range of 1.2 eV. This frequency peak shift is rooted in the asymmetry exhibited by the rising and falling edges of the laser pulse, directly influencing the position of the peak frequency emission. Our study quantifies the dependence of this tuning range and the asymmetry of the laser pulse, offering valuable insights into the underlying mechanisms driving this phenomenon. Furthermore, our investigation uncovers the emergence of semi-integer order harmonics as the phase parameter is altered. We attribute this discovery to the intricate interference between harmonics generated by the primary and secondary return cores. This observation introduces an innovative approach for generating semi-integer order harmonics, thus expanding our understanding of high-order harmonic generation. Ultimately, our work contributes to the broader comprehension of complex phenomena in laser-matter interactions and provides a foundation for harnessing these effects in various applications, particularly those involving precise spectral control and the generation of unique harmonic patterns. Select Controllable optical bistability in a Fabry-Pérot cavity with a nonlinear three-dimensional Dirac semimetal Hong-Xia Yuan(袁红霞), Jia-Xue Li(李佳雪), Qi-Jun Ma(马奇军), Hai-Shan Tian(田海山),Yun-Yang Ye(叶云洋), Wen-Xin Luo(罗文昕), Xing-Hua Wu(吴杏华), and Le-Yong Jiang(蒋乐勇) Chin. Phys. B, 2024, 33 (3): 034213.   DOI: 10.1088/1674-1056/acfdfe Abstract （38）   HTML （0）    PDF （1223KB）（24）       Knowledge map    Optical bistability (OB) is capable of rapidly and reversibly transforming a parameter of an optical signal from one state to another, and homologous nonlinear optical bistable devices are core components of high-speed all-optical communication and all-optical networks. In this paper, we theoretically investigated the controllable OB from a Fabry-Pérot (FP) cavity with a nonlinear three-dimensional Dirac semimetal (3D DSM) in the terahertz band. The OB stems from the third-order nonlinear bulk conductivity of the 3D DSM and the resonance mode has a positive effect on the generation of OB. This FP cavity structure is able to tune the OB because the transmittance and the reflectance can be modulated by the Fermi energy of the 3D DSM. We believe that this FP cavity configuration could provide a reference concept for realizing tunable bistable devices. Select Decoupling of temporal/spatial broadening effects in Doppler wind LiDAR by 2D spectral analysis Zhen Liu(刘珍), Yun-Peng Zhang(张云鹏), Xiao-Peng Zhu(竹孝鹏), Ji-Qiao Liu(刘继桥), De-Cang Bi(毕德仓), and Wei-Biao Chen(陈卫标) Chin. Phys. B, 2024, 33 (3): 034214.   DOI: 10.1088/1674-1056/ad10fd Abstract （46）   HTML （2）    PDF （700KB）（37）       Knowledge map    Pulse echo accumulation is commonly employed in coherent Doppler wind LiDAR (light detection and ranging) under the assumption of steady wind. Here, the measured spectral data are analyzed in the time dimension and frequency dimension to cope with the temporal wind shear and achieve the optimal accumulation time. A hardware-efficient algorithm combining the interpolation and cross-correlation is used to enhance the wind retrieval accuracy by reducing the frequency sampling interval and then reduce the spectral width calculation error. Moreover, the temporal broadening effect and spatial broadening effect are decoupled according to the strategy we developed. Select High-efficiency ultra-fast all-optical photonic crystal diode based on the lateral-coupled nonlinear elliptical defect Daxing Li(李大星), Kaizhu Liu(刘凯柱), Chunlong Yu(余春龙), Kuo Zhang(张括),Yueqin Liu(刘跃钦), and Shuai Feng(冯帅) Chin. Phys. B, 2024, 33 (3): 034215.   DOI: 10.1088/1674-1056/ad0117 Abstract （36）   HTML （1）    PDF （2264KB）（11）       Knowledge map    An all-optical Fano-like diode featuring a nonlinear lateral elliptical micro-cavity and a reflecting column in the photonic crystal waveguide is proposed. The asymmetric micro-cavity is constructed by removing one rod and changing the shape of the lateral rod from a circle to an ellipse. A reflecting pillar is also introduced into the waveguide to construct an F-P cavity with the elliptical defect and enhance the asymmetric transmission for the incident light wave transmitting rightwards and leftwards, respectively. By designing the size of the ellipse and optimizing a reflecting rod at a suitable position, a maximum forward light transmittance of -1.14 dB and a minimum backward transmittance of -57.66 dB are achieved at the working wavelength of 1550.47 nm. The corresponding response time is about 10 ps when the intensity of the pump light beam resonant at 637 nm is 3.97 W/μm2. Select High-order Bragg forward scattering and frequency shift of low-frequency underwater acoustic field by moving rough sea surface Ya-Xiao Mo(莫亚枭), Chao-Jin Zhang(张朝金), Li-Cheng Lu(鹿力成), Qi-Hang Sun(孙启航), and Li Ma(马力) Chin. Phys. B, 2024, 33 (3): 034301.   DOI: 10.1088/1674-1056/ad108f Abstract （33）   HTML （1）    PDF （7345KB）（26）       Knowledge map    Acoustic scattering modulation caused by an undulating sea surface on the space-time dimension seriously affects underwater detection and target recognition. Herein, underwater acoustic scattering modulation from a moving rough sea surface is studied based on integral equation and parabolic equation. And with the principles of grating and constructive interference, the mechanism of this acoustic scattering modulation is explained. The periodicity of the interference of moving rough sea surface will lead to the interference of the scattering field at a series of discrete angles, which will form comb-like and frequency-shift characteristics on the intensity and the frequency spectrum of the acoustic scattering field, respectively, which is a high-order Bragg scattering phenomenon. Unlike the conventional Doppler effect, the frequency shifts of the Bragg scattering phenomenon are multiples of the undulating sea surface frequency and are independent of the incident sound wave frequency. Therefore, even if a low-frequency underwater acoustic field is incident, it will produce obvious frequency shifts. Moreover, under the action of ideal sinusoidal waves, swells, fully grown wind waves, unsteady wind waves, or mixed waves, different moving rough sea surfaces create different acoustic scattering processes and possess different frequency shift characteristics. For the swell wave, which tends to be a single harmonic wave, the moving rough sea surface produces more obvious high-order scattering and frequency shifts. The same phenomena are observed on the sea surface under fully grown wind waves, however, the frequency shift slightly offsets the multiple peak frequencies of the wind wave spectrum. Comparing with the swell and fully-grown wind waves, the acoustic scattering and frequency shift are not obvious for the sea surface under unsteady wind waves. Select Wave nature of Rosensweig instability Liu Li(李柳), Decai Li(李德才), Zhiqiang Qi(戚志强), Lu Wang(王璐), and Zhili Zhang(张志力) Chin. Phys. B, 2024, 33 (3): 034701.   DOI: 10.1088/1674-1056/ad1485 Abstract （26）   HTML （0）    PDF （9156KB）（7）       Knowledge map    The explicit analytical solution of Rosensweig instability spikes' shapes obtained by Navier-Stokes (NS) equation in diverse magnetic field H vertical to the flat free surface of ferrofluids are systematically studied experimentally and theoretically. After carefully analyzing and solving the NS equation in elliptic form, the force balanced surface equations of spikes in Rosensweig instability are expressed as cosine wave in perturbated magnetic field and hyperbolic tangent in large magnetic field, whose results both reveal the wave-like nature of Rosensweig instability. The results of hyperbolic tangent form are perfectly fitted to the experimental results in this paper, which indicates that the analytical solution is basically correct. Using the forementioned theoretical results, the total energy of the spike distribution pattern is calculated. By analyzing the energy components under different magnetic field intensities H, the hexagon-square transition of Rosensweig instability is systematically discussed and explained in an explicit way. Select A flexible ultra-broadband multi-layered absorber working at 2 GHz-40 GHz printed by resistive ink Tao Wang(汪涛), Yu-Lun Yan(闫玉伦), Gong-Hua Chen(陈巩华), Ying Li(李迎), Jun Hu(胡俊), and Jian-Bo Mao(毛剑波) Chin. Phys. B, 2024, 33 (2): 024101.   DOI: 10.1088/1674-1056/acea64 Abstract （62）   HTML （3）    PDF （1800KB）（64）       Knowledge map    A flexible extra broadband metamaterial absorber (MMA) stacked with five layers working at 2 GHz-40 GHz is investigated. Each layer is composed of polyvinyl chloride (PVC), polyimide (PI), and a frequency selective surface (FSS), which is printed on PI using conductive ink. To investigate this absorber, both one-dimensional analogous circuit analysis and three-dimensional full-wave simulation based on a physical model are provided. Various crucial electromagnetic properties, such as absorption, effective impedance, complex permittivity and permeability, electric current distribution and magnetic field distribution at resonant peak points, are studied in detail. Analysis shows that the working frequency of this absorber covers entire S, C, X, Ku, K and Ka bands with a minimum thickness of 0.098 λmax (λmax is the maximum wavelength in the absorption band), and the fractional bandwidth (FBW) reaches 181.1%. Moreover, the reflection coefficient is less than -10 dB at 1.998 GHz-40.056 GHz at normal incidence, and the absorptivity of the plane wave is greater than 80% when the incident angle is smaller than 50°. Furthermore, the proposed absorber is experimentally validated, and the experimental results show good agreement with the simulation results, which demonstrates the potential applicability of this absorber at 2 GHz-40 GHz. Select Wideband low-scattering metasurface with an in-band reconfigurable transparent window Ying Zhu(朱瑛), Weixu Yang(杨维旭), Kun Duan(段坤), Tian Jiang(姜田), Junming Zhao(赵俊明), Ke Chen(陈克), and Yijun Feng(冯一军) Chin. Phys. B, 2024, 33 (2): 024102.   DOI: 10.1088/1674-1056/ad0119 Abstract （54）   HTML （0）    PDF （4886KB）（88）       Knowledge map    Active metasurfaces with dynamically reconfigurable functionalities are highly demanded in various practical applications. Here, we propose a wideband low-scattering metasurface that can realize an in-band reconfigurable transparent window by altering the operation states of the PIN diodes loaded on the structures. The metasurface is composed of a band-pass frequency selective surface (FSS) sandwiched between two polarization conversion metasurfaces (PCMs). PIN diodes are integrated into the FSS to switch the transparent window, while a checkerboard configuration is applied in PCMs for the diffusive-reflective function. A sample with 20×20 elements is designed, fabricated, and experimentally verified. Both simulated and measured results show that the in-band functions can be dynamically switched between beam-splitting scattering and high transmission by controlling the biasing states of the diodes, while low backscattering can be attained outside the passband. Furthermore, the resonant structures of FSS also play the role of feeding lines, thus significantly eliminating extra interference compared with conventional feeding networks. We envision that the proposed metasurface may provide new possibilities for the development of an intelligent stealth platform and its antenna applications. page Page 1 of 120 Total 2383 records First page Prev page Next page Last page